Add support for check-and-put and check-and-delete (#13)
0.3.3 changes
- PUT will not store null values (#15)
- `filter(column: nil)` will match rows without the column
- `filter(column: value)` will *NOT* match rows without the column
- Added `HBase::Table#check` method for CAS operations (#14)
- Fix: invalid count when filter is used
Merge pull request #16 from junegunn/devel

Merge 0.3.3 changes